Velocity measurement

In addition to the pure position value, a velocity value can also be calculated and output (EL5032: from firmware 16, Revision 28 /EL5032-0090: from Revision 17).

Procedure of velocity measurement

The velocity is calculated from the change of the position value in a defined time interval.
The result is output via the process data either in index 0x60n8:12 "Velocity" or in index 0x60n8:13 "Velocity (int16)" (n = 0 for channel 1, n = 1 for channel 2).

• Selection of the velocity window in index 0x80n8:17 "Velocity window"
• Default: 10 ms
• Follow the instructions below to select the correct timeframe.
• The velocity value can be normalized over the two indices:
• 0x80n8:15 "Velocity numerator"
• 0x80n8:16 "Velocity denominator".
• Additionally, a digital filter can be set (see chapter "Filter operation")
• The calculated velocity value is output:
• either via 0x60n8:12 "Velocity"
• or via 0x60n8:13 "Velocity (int16)"
• The calculation is carried out acyclically and without reference to the distributed clock system and is therefore independent of the operation mode.

Correct selection of the timeframe

The timeframe for measuring the velocity is set to 10 ms in the delivery state. It is always a multiple of the cycle time, and is rounded up to the next larger value. This is due to technical reasons, because the position value is internally available only once per PLC cycle.

The accuracy of the determined velocity depends on the size of the timeframe (0x80n8:17 "Velocity window"). This must be selected according to the application.

• At constant velocities, select a larger timeframe so that the best possible averaging can take place.
• In situations where frequent positive or negative accelerations are encountered, select a smaller timeframe in order to be able to respond more quickly to changing position values.